<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
promise_test(async (t) => {
  let start_length = navigation.entries().length;
  let start_index = navigation.currentEntry.index;

  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  await new Promise(r => window.onload = () => t.step_timeout(r, 0));
  await navigation.navigate("#1").finished;
  assert_equals(navigation.entries().length, start_length + 1);

  let iframe = document.createElement("iframe");
  iframe.src = "/common/blank.html";
  document.body.appendChild(iframe);
  await new Promise(r => iframe.onload = () => t.step_timeout(r, 0));
  assert_equals(iframe.contentWindow.navigation.entries().length, 1);

  // Go back to before the iframe was added. The iframe will still be in the
  // document, but we will be at a joint session history entry that was created
  // before the iframe was added to the document.
  await navigation.back().finished;
  assert_equals(navigation.entries().length, start_length + 1);
  assert_equals(iframe.contentWindow.navigation.entries().length, 1);
  assert_equals(navigation.currentEntry.index, start_index);
  assert_equals(iframe.contentWindow.navigation.currentEntry.index, 0);

  // A push navigation in the top window will truncate-then-push the joint
  // session history. This should dispose the forward entry in the top window,
  // but should not interfere with the currentEntry in the iframe.
  let dispose_promise = new Promise(r => navigation.entries()[start_index + 1].ondispose = r);
  iframe.contentWindow.navigation.currentEntry.ondispose = t.unreached_func("iframe entry must not be disposed");
  await navigation.navigate("#b").finished;

  await dispose_promise;
  assert_equals(navigation.entries().length, start_length + 1);
  assert_equals(iframe.contentWindow.navigation.entries().length, 1);
  assert_equals(navigation.currentEntry.index, start_index + 1);
  assert_equals(iframe.contentWindow.navigation.currentEntry.index, 0);
}, "Removing a currentEntry from the joint session history shouldn't dispose it");
</script>
